Electronic circuit having display driving function, touch sensing function and fingerprint sensing function

ABSTRACT

An electronic circuit adapted to drive a display panel is provided. The display panel includes touch sensors and fingerprint sensors. The electronic circuit includes a touch sensing circuit, a fingerprint sensing circuit and a display driving circuit. The touch sensing circuit senses a touch of a finger and determines a first area corresponding to the touch on the display panel. The fingerprint sensing circuit senses a fingerprint image of the finger corresponding to the first area. The display driving circuit drives pixels of the first area with respective first gray levels and pixels of a second area outside the first area with respective second gray levels. The display driving circuit processes respective third gray levels to obtain the respective second gray levels. The display driving circuit generates gamma voltages corresponding to the respective first gray levels and the respective second gray levels according to the same gamma curve.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims thepriority benefit of U.S. patent application Ser. No. 16/921,921, filedon Jul. 6, 2020, now allowed. The prior U.S. patent application Ser. No.16/921,921 claims the priority benefit of U.S. Provisional applicationSer. No. 62/889,572, filed on Aug. 21, 2019. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND Technical Field

The invention relates to an electronic circuit and a driving method,more specifically, to an electronic circuit adapted to drive a displaypanel including touch sensors and fingerprint sensors and a method fordriving the display panel.

Description of Related Art

In recent years, demands for fingerprint sensing have been graduallyincreased. In order to reduce a volume of an electronic device, afingerprint sensing region may overlap with a display region of theelectronic device. For example, an under-display fingerprintidentification technique is to embed fingerprint sensors to a displaypanel, and the fingerprint sensor may sense or capture a fingerprintimage through the display panel. When a touch event such as fingerprintidentification happens, a touch sensing circuit may report it to anapplication processor of the electronic device via a specifiedinterface. Next, the application processor further controls a displaydriving circuit to drive the display panel to display image forfingerprint sensing. The display driving circuit may control a backlightcontroller to adjust the backlight of the display panel based on theinstruction of the application processor. The whole backlight may beturned on to have the highest brightness. However, the high brightnessof the display panel may let users feel uncomfortable.

On the other hand, the application processor further controls afingerprint sensing circuit to perform the fingerprint sensingoperation. The fingerprint sensing circuit transmits sensing informationto the application processor for fingerprint identification after thefingerprint sensing operation, and then the application processorcompletes the fingerprint identification according to the sensinginformation. However, the touch sensing circuit needs to report thetouch event to the application processor, and the display drivingcircuit and the fingerprint sensing circuit operating for displayingimages and fingerprint sensing are based on the instruction of theapplication processor. Therefore, it may spend more time for fingerprintsensing and identification.

SUMMARY

The invention is directed to an electronic circuit, capable of providingan efficient method for fingerprint sensing and identification and gooduser experience for users. A method for driving display panel by usingthe electronic circuit is also provided.

An embodiment of the invention provides an electronic circuit adapted todrive a display panel. The display panel includes touch sensors andfingerprint sensors. The electronic circuit includes a touch sensingcircuit, a fingerprint sensing circuit and a display driving circuit.The touch sensing circuit is configured to sense a touch of a finger anddetermine a first area corresponding to the touch on the display panel.The fingerprint sensing circuit is configured to sense a fingerprintimage of the finger corresponding to the first area of the displaypanel. The display driving circuit is configured to drive pixels of thefirst area with respective first gray levels and pixels of a second areaoutside the first area with respective second gray levels. The displaydriving circuit processes respective third gray levels to obtain therespective second gray levels. The display driving circuit generatesgamma voltages corresponding to the respective first gray levels and therespective second gray levels according to a same gamma curve.

An embodiment of the invention provides an electronic circuit adapted todrive a display panel. The display panel includes touch sensors andfingerprint sensors. The electronic circuit includes a touch sensingcircuit, a fingerprint sensing circuit and a display driving circuit.The touch sensing circuit is configured to sense a touch of a finger anddetermine a first area corresponding to the touch on the display panel.The fingerprint sensing circuit is configured to sense a fingerprintimage of the finger corresponding to the first area of the displaypanel. The display driving circuit is configured to drive pixels of thefirst area with respective first gray levels and pixels of a second areaoutside the first area with respective second gray levels. The displaydriving circuit generates first gamma voltages corresponding to therespective first gray levels according to a first gamma curve in anoperation mode, and the display driving circuit generates second gammavoltages corresponding to the respective second gray levels according toa second gamma curve in the operation mode.

An embodiment of the invention provides an electronic circuit adapted todrive a display panel. The display panel includes touch sensors andfingerprint sensors. The electronic circuit includes a touch sensingcircuit, a fingerprint sensing circuit, a first interface circuit, adisplay driving circuit and a second interface circuit. The touchsensing circuit is configured to sense a touch of a finger and determinea first area corresponding to the touch on the display panel. Thefingerprint sensing circuit is configured to sense a fingerprint imageof the finger corresponding to the first area of the display panel. Thetouch sensing circuit, via the first interface circuit, controls thefingerprint sensing circuit to scan the first area and sense thefingerprint image from the first area. The display driving circuit isconfigured to drive pixels of the first area of the display panel. Thetouch sensing circuit, via the second interface circuit, controls thedisplay driving circuit to drive the pixels of the first area. Theelectronic circuit is implemented in a single semiconductor chip, andthe first interface circuit and the second interface circuit aredisposed inside the single semiconductor chip.

An embodiment of the invention provides an electronic circuit adapted todrive a display panel. The display panel includes touch sensors andfingerprint sensors. The electronic circuit includes a touch sensingcircuit, a fingerprint sensing circuit, a first interface circuit, adisplay driving circuit and a second interface circuit. The touchsensing circuit is configured to sense a touch of a finger and determinea first area corresponding to the touch on the display panel. Thefingerprint sensing circuit is configured to sense a fingerprint imageof the finger corresponding to the first area of the display panel. Thetouch sensing circuit, via the first interface circuit, controls thefingerprint sensing circuit to scan the first area and sense thefingerprint image of the finger from the first area. The display drivingcircuit is configured to drive pixels of the first area of the displaypanel. The touch sensing circuit, via the second interface circuit,controls the display driving circuit to drive the pixels of the firstarea. The electronic circuit is implemented in at least twosemiconductor chips includes a first semiconductor chip and a secondsemiconductor chip. The first semiconductor chip includes the touchsensing circuit and the display driving circuit. The secondsemiconductor chip includes the fingerprint sensing circuit. The secondinterface circuit is disposed inside the first semiconductor chip, andthe first semiconductor chip and the second semiconductor chipcommunicate with each other via the first interface circuit.

An embodiment of the invention provides a method for driving a displaypanel. The display panel includes touch sensors and fingerprint sensors.The method includes: sensing a touch of a finger to determine a firstarea corresponding to the touch on the display panel; sensing afingerprint image of the finger corresponding to the first area of thedisplay panel; driving pixels of the first area with respective firstgray levels and pixels of a second area outside the first area withrespective second gray levels; processing respective third gray levelsto obtain the respective second gray levels; and generating gammavoltages corresponding to the respective first gray levels and therespective second gray levels according to a same gamma curve.

An embodiment of the invention provides a method for driving a displaypanel. The display panel includes touch sensors and fingerprint sensors.The method includes: sensing a touch of a finger to determine a firstarea corresponding to the touch on the display panel; sensing afingerprint image of the finger corresponding to the first area of thedisplay panel; driving pixels of the first area with respective firstgray levels and pixels of a second area outside the first area withrespective second gray levels; generating first gamma voltagescorresponding to the respective first gray levels according to a firstgamma curve in an operation mode; and generating second gamma voltagescorresponding to the respective second gray levels according to a secondgamma curve in the operation mode.

To make the aforementioned more comprehensible, several embodimentsaccompanied with drawings are described in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate exemplaryembodiments of the disclosure and, together with the description, serveto explain the principles of the disclosure.

FIG. 1 is a schematic block diagram illustrating an electronic deviceaccording to an embodiment of the invention.

FIG. 2 is a schematic diagram illustrating the display panel depicted inFIG. 1 .

FIG. 3 is a schematic block diagram illustrating the electronic circuitdepicted in FIG. 1 .

FIG. 4 is a schematic block diagram illustrating an electronic deviceaccording to another embodiment of the invention.

FIG. 5 illustrates the electronic device depicted in FIG. 4 operating ina first operation mode according to an embodiment of the invention.

FIG. 6 illustrates the electronic device depicted in FIG. 4 operating ina second operation mode according to an embodiment of the invention.

FIG. 7 is a flowchart illustrating steps in a method for fingerprintidentification according to an embodiment of the invention.

FIG. 8 is a schematic block diagram illustrating an electronic deviceaccording to another embodiment of the invention.

FIG. 9 illustrates a voltage conversion operation according to anembodiment of the invention.

FIG. 10 illustrates a data processing operation according to anembodiment of the invention.

FIG. 11 is a flowchart illustrating steps in a method for driving adisplay panel according to an embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

Embodiments are provided below to describe the disclosure in detail,though the disclosure is not limited to the provided embodiments, andthe provided embodiments can be suitably combined. The term“coupling/coupled” or “connecting/connected” used in this specification(including claims) of the application may refer to any direct orindirect connection means. For example, “a first device is coupled to asecond device” should be interpreted as “the first device is directlyconnected to the second device” or “the first device is indirectlyconnected to the second device through other devices or connectionmeans.” The term “signal” can refer to a current, a voltage, a charge, atemperature, data, electromagnetic wave or any one or multiple signals.In addition, the term “and/or” can refer to “at least one of”. Forexample, “a first signal and/or a second signal” should be interpretedas “at least one of the first signal and the second signal”.

FIG. 1 is a schematic block diagram illustrating an electronic deviceaccording to an embodiment of the invention. Referring to FIG. 1 , theelectronic device 100 of the present embodiment includes an electroniccircuit 110 and a display panel 120. The display panel 120 includestouch sensors and fingerprint sensors. The electronic circuit 110 isconfigurable to be coupled to the display panel 120. The electroniccircuit 110 is adapted to drive the display panel 120.

In the present embodiment, the electronic device 100 may be anelectronic device having a display function, a touch sensing functionand a fingerprint sensing function. In an embodiment, the electronicdevice 100 may be, but not limited to, a smartphone, a non-smart phone,a wearable electronic device, a tablet computer, a personal digitalassistant, a notebook and other portable electronic devices that canoperate independently and have the display function, the touch sensingfunction and the fingerprint sensing function. In an embodiment, theelectronic device 100 may be, but not limited to, a portable orun-portable electronic device in a vehicle intelligent system. In anembodiment, the electronic device 100 may be, but not limited to,intelligent home appliances such as, a television, a computer, arefrigerator, a washing machine, a telephone, an induction cooker, atable lamp and so on.

FIG. 2 is a schematic diagram illustrating the display panel depicted inFIG. 1 . Referring to FIG. 2 , the display panel 120 of the presentembodiment includes a plurality of display pixels 122, a plurality oftouch sensors 124 and a plurality of fingerprint sensors 126. Theelectronic circuit 110 drives and controls the display panel 120 toperform a display operation, a touch sensing operation and a fingerprintsensing operation. To be specific, the electronic circuit 110 drives andcontrols the display pixels 122 to display images via display scan linesGDL and display data lines SDL. The electronic circuit 110 also drivesand controls the touch sensors 124 to sense a touch event of the displaypanel 120 via touch scan lines and touch sensing lines TSL. In anembodiment, the touch sensors 124 may be touch sensing electrodes in atouch sensing phase, and the touch sensors 124 may be common electrodesin a display phase. In the present embodiment, in-cell touch sensors aredepicted in FIG. 2 as an example. For the in-cell touch sensors, thedisplay panel 120 inherently has no touch scan lines. For other typetouch sensors, the display panel 120 may have touch scan lines fortransmitting touch driving signals. The electronic circuit 110 alsodrives and controls the fingerprint sensors 126 to sense a fingerprintimage on the display panel 120 via fingerprint scan lines GSL andfingerprint sensing lines FSL.

In an embodiment, the display panel 120 may be an in-cell fingerprint,touch and display panel that the fingerprint sensors and the touchsensors are embedded, but the invention is not limited thereto. In anembodiment, the electronic circuit 110 may drive and control theelectronic device 100 to perform an in-display fingerprintidentification operation, i.e. fingerprint recognition operation. In anembodiment, the fingerprint sensors 126 may be optical fingerprintsensors.

FIG. 3 is a schematic block diagram illustrating the electronic circuitdepicted in FIG. 1 . Referring to FIG. 3 , the electronic circuit 110may include a display driving circuit 112, a fingerprint sensing circuit116 and a touch sensing circuit 114. The display driving circuit 112 isconfigured to drive and control the display pixels 122 to display imagesvia the display scan lines GDL and the display data lines SDL. Thedisplay driving circuit 112 generates display driving signals fordriving the display data lines SDL of the display panel 120. The displaydriving circuit 112 may include a timing controller 121, a displaydriver and other functional circuits for the display operation. Thedisplay driving circuit 112 may also include other controllers orprocessors 123 for other control activities of the display operation.The touch sensing circuit 114 is configured to drive and control thetouch sensors 124 to sense the touch event of the display panel 120 viathe touch sensing lines TSL. The touch sensing circuit 114 may include atouch controller 141, an analog front end (AFE) circuit, ananalog-to-digital converter (ADC) circuit and other functional circuitsfor the touch sensing operation. The fingerprint sensing circuit 116 isconfigured to drive and control the fingerprint sensors 126 to sense thefingerprint on the display panel 120 via the fingerprint scan lines GSLand the fingerprint sensing lines FSL. The fingerprint sensing circuit116 receives fingerprint sensing signals corresponding to a fingerprintimage from the fingerprint sensors 126 and may also process thefingerprint sensing signals to obtain the fingerprint image. Thefingerprint sensing circuit 116 may include a digital circuit 161, anAFE circuit, an ADC circuit and other functional circuits for thefingerprint sensing operation.

In an embodiment, when the electronic circuit 110 is implemented as asingle chip integrated circuit that can drive and control the displaypanel 120 to perform the display operation, the touch sensing operationand the fingerprint sensing operation, the electronic circuit 110 mayinclude a control circuit 130, and the control circuit 130 may be amicro-controller based core to perform all of control activities of thedisplay operation, the touch sensing operation and the fingerprintsensing operation. The control circuit 130 may include at least one ofthe timing controller 121, the touch controller 141, the digital circuit161, and the other controllers or processors 123 of the display drivingcircuit 112.

The display driving circuit 112, the touch sensing circuit 114 and thefingerprint sensing circuit 116 communicate with one another via signaltransmission interfaces, such as Mobile Industry Processor Interface(MIPI), Inter-Integrated Circuit (I2C) Interface, Serial PeripheralInterface (SPI) and/or other similar or suitable interfaces.

Regarding hardware structures of the components in the embodiment ofFIG. 3 , the timing controller 121, the touch controller 141 and thedigital circuit 161 may be a processor having computational capability.Alternatively, the timing controller 121, the touch controller 141 andthe digital circuit 161 may be designed through hardware descriptionlanguages (HDL) or any other design methods for digital circuitsfamiliar to people skilled in the art and may be hardware circuitsimplemented through a field programmable gate array (FPGA), a complexprogrammable logic device (CPLD), or an application-specific integratedcircuit (ASIC). In addition, enough teaching, suggestion, andimplementation illustration for hardware structures of the displaydriving circuit 112, the touch sensing circuit 114 and the fingerprintsensing circuit 116 can be obtained with reference to common knowledgein the related art, which is not repeated hereinafter.

FIG. 4 is a schematic block diagram illustrating an electronic deviceaccording to another embodiment of the invention. Referring to FIG. 4 ,the electronic device 200 of the present embodiment includes theelectronic circuit 110, the display panel 120, an application processor230 and a backlight module 240. The electronic circuit 110 includes thedisplay driving circuit 112, the touch sensing circuit 114, thefingerprint sensing circuit 116, a first interface circuit IF1 and asecond interface circuit IF2. The first interface circuit IF1 includescircuits for transmitting and receiving signals arranged in the touchsensing circuit 114 and/or the fingerprint sensing circuit 116. Thesecond interface circuit IF2 includes circuits for transmitting andreceiving signals arranged in the touch sensing circuit 114 and/or thedisplay driving circuit 112. The touch sensing circuit 114 and thefingerprint sensing circuit 116 communicate with each other via thefirst interface circuit IF1. The display driving circuit 112 and thetouch sensing circuit 114 communicate with each other via the secondinterface circuit IF2.

In the present embodiment, the electronic circuit 110 co-operates withthe display panel 120 and the application processor 230 for afingerprint identification operation. The electronic circuit 110 outputsa fingerprint image to a trust zone 232 of the application processor 230to perform the fingerprint identification operation, i.e. a fingerprintrecognition operation. Enough teaching, suggestion, and implementationillustration for the fingerprint identification operation can beobtained with reference to common knowledge in the related art, which isnot repeated hereinafter.

FIG. 5 illustrates the electronic device depicted in FIG. 4 operating ina first operation mode according to an embodiment of the invention. Thefirst operation mode, for example, may be operated when users login inthe electronic device 200 at a power on state, or re-sign in theelectronic device 200 from an idle state. Referring to FIG. 4 and FIG. 5, the electronic device 200 of the present embodiment may be asmartphone or a similar device that has an application processor 230,but the invention is not limited thereto. In the first operation mode,the display driving circuit 112 drives pixels over the display panel 120with respective first gray levels during a first phase. Therefore, adark screen is displayed on the whole of the display panel 120 before afirst area 310 is displayed (the first phase). During the first phase,the fingerprint sensing circuit 116 may be idle and work in a powersaving mode. The touch sensing circuit 114 is configured to sense atouch of a finger and determine the first area 310 corresponding to thetouch on the display panel 120. The touch sensing circuit 114, via thesecond interface circuit IF2, controls the display driving circuit 112to drive the pixels of the first area 310 with respective second graylevels and the pixels of a second area 320 outside the first area 310with respective third gray levels during a second phase later than thefirst phase. In present embodiment, the respective second gray levelsare higher than the respective first gray levels, and the respectivethird gray levels are lower than the respective second gray levels.Therefore, the first area 310 with a high brightness is displayed on thedisplay panel 120 and can serve as a fingerprint input region after thefirst area 310 is displayed (the second phase). During the second phase,the fingerprint sensing circuit 116 works in a normal power mode. Thebrightness of the backlight in the second phase is larger than that inthe first phase. The first area 310 may be displayed as a white regionor a region with a predetermined color. The dark screen may be stilldisplayed on the second area 320. In this case, the respective thirdgray levels are substantially the same as the respective first graylevels.

The touch sensing circuit 114 includes a touch controller 141 and an AFEcircuit 143. The AFE circuit 143 receives a touch sensing signal S1 fromthe display panel 120 and processes and transmits the touch sensingsignal S1 to the touch controller 141. The touch controller 141determines the first area 310 corresponding to the touch on the displaypanel 120 according to the touch sensing signal S1. The touch controller141 may obtain coordinate information and size information of the touchto determine the first area 310 accordingly. The size and shape of thefirst area may be predetermined or may depend on the size and shape ofthe detected touch area. In an embodiment, the first area is determinedwith suitable size and shape such that it can be completely covered bythe finger as scanning fingerprint. In an embodiment, the AFE circuit143 may transmit a touch driving signal to the touch sensors 124 of FIG.2 and receive the touch sensing signal S1 therefrom. The touch sensingsignal S1 is transmitted to the touch controller 141 for judging if atouch happens or not.

The touch sensing circuit 114, via the second interface circuit IF2,controls the display driving circuit 112. The display driving circuit112 is configured to drive pixels of the first area 310 of the displaypanel 120 with a display pattern indicating the fingerprint inputregion. The display driving circuit 112 includes a timing controller 121and a display driver 125. The display driver 125 drives the displaypanel 120 to display images via driving signals S2. In the presentembodiment, the display driver 125 drives the display panel 120 todisplay a circular area (the first area 310) to indicate the fingerprintinput region, but the invention is not limited thereto. In otherembodiments, the display pattern may be displayed as any suitable formfor fingerprint input. Enough teaching, suggestion, and implementationillustration for the method for controlling and driving the displaypanel 120 can be obtained with reference to common knowledge in therelated art, which is not repeated hereinafter.

In the present embodiment, the touch sensing circuit 114, via the secondinterface circuit IF2, controls the display driving circuit 112 toadjust the backlight module 240 of the electronic device 200 by a pulsewidth modulation (PWM) signal S6. For example, the touch controller 141may inform the display driving circuit 112, and then a backlightcontroller of the display driving circuit 112 outputs the PWM signal S6to adjust the brightness of backlight by adjusting a duty ratio of thePWM signal S6. Also, a frequency of the PWM signal can be adjusted. Byadjusting the frequency of the PWM signal S6, an optimized frequency canbe provided to the backlight module 240. Therefore, the first area 310with a high brightness is displayed on the display panel 120 to serve asthe fingerprint input region. The first area 310 may be displayed as awhite region or a region with a predetermined color. The dark screen maybe still displayed on a second area 320 outside the first area 310.

On the other hand, the touch controller 141 determines whether the touchis valid. When the detected touch area of the touch is larger than apredetermined threshold area, the touch controller 141 determines thetouch as a valid touch. That is to say, the touch is recognized valid ifthe detected touch area is larger than the predetermined threshold area.The touch controller 141, via the first interface circuit IF1, controlsthe fingerprint sensing circuit 116 to initiate the fingerprint scanningfor the first area 310 when the valid touch happens. In otherembodiments, the touch controller 141 may determine whether the touch isvalid according to shape, strength and/or touch times of the touch. Forexample, a double click or a long-time touch may be determined as avalid touch.

Compared to the global display region of the display panel 120, thefirst area 310 is a local display region of the display panel 120 forfingerprint input, such that the speed of the fingerprint scanning maybecome faster. The fingerprint sensing circuit 116 is configured tosense the fingerprint image of the finger corresponding to the firstarea 310 of the display panel 120. The fingerprint sensing circuit 116includes a digital circuit 161, an AFE circuit 163 and a gate driver165. The gate driver 165 drives the fingerprint sensors 126corresponding to the first area 310 to perform the fingerprint sensingoperation via a driving signal S4, and thus the fingerprint sensors 126corresponding to the first area 310 transmit a fingerprint sensingsignal S3 to the AFE circuit 163. The AFE circuit 163 receives thefingerprint sensing signal S3 from the display panel 120 and processesand transmits the fingerprint sensing signal S3 to the digital circuit161. Next, the digital circuit 161 generates and transmits thefingerprint image to the application processor 230 for the fingerprintidentification operation via an interface (e.g. SPI in FIG. 4 ) betweenthe application processor 230 and the electronic circuit 110.

In the present embodiment, the fingerprint sensing circuit 116 may workin the normal power mode or the power saving mode. During the secondphase, the touch controller 141 wakes up the fingerprint sensing circuit116 from the power saving mode to the normal power mode, and outputs thelocation and size information of the first area 310 to the fingerprintsensing circuit 116 via the first interface circuit IF1. The fingerprintsensing circuit 116 initiates the fingerprint scanning for the firstarea 310. In an embodiment, when the fingerprint scanning is performed,the gate driver 165 drives the fingerprint scan lines GSL correspondingto the first area 310 that are arranged in a Y-direction, and the AFEcircuit 163 receives the fingerprint sensing signal S3 from thefingerprint sensing lines FSL corresponding to the first area 310 thatare arranged in an X-direction. The fingerprint scanning is performedonly for the first area 310 determined by the touch controller 141 inthe embodiment.

In the present embodiment, the first interface circuit IF1 is locatedbetween the touch sensing circuit 114 and the fingerprint sensingcircuit 116, and the second interface circuit IF2 is located between thetouch sensing circuit 114 and the display driving circuit 112. The touchsensing circuit 114 directly controls the display driving circuit 112 toadjust the backlight and display the fingerprint input region via thesecond interface circuit IF2 without via the application processor 230.The touch sensing circuit 114 directly controls the fingerprint sensingcircuit 116 to perform the fingerprint scanning and sensing operationvia the first interface circuit IF1 without via the applicationprocessor 230. The time for performing the fingerprint scanning andsensing operation can be reduced.

Regarding hardware structures of the components in the embodiment ofFIG. 4 , the timing controller 121, the touch controller 141 and thedigital circuit 161 may be processors having computational capability.Alternatively, the timing controller 121, the touch controller 141 andthe digital circuit 161 may be designed through hardware descriptionlanguages (HDL) or any other design methods for digital circuitsfamiliar to people skilled in the art and may be hardware circuitsimplemented through a field programmable gate array (FPGA), a complexprogrammable logic device (CPLD), or an application-specific integratedcircuit (ASIC).

FIG. 6 illustrates the electronic device depicted in FIG. 4 operating ina second operation mode according to an embodiment of the invention.Referring to FIG. 4 and FIG. 6 , the electronic device 200 is not idlein the second operation mode. At least one part region 330 of thedisplay panel 120 with a brightness higher than a dark screen isdisplayed in the second operation mode for some application, such asmobile payment or bank login, but the invention is not limited thereto.In an embodiment, a bright screen may be displayed on the whole of thedisplay panel 120 during the first phase in the second operation mode.The brightness of the bright screen is not as high as that of the firstarea 310 to be displayed during the second phase. The first area 310with a high brightness is displayed on the display panel 120 to serve asthe fingerprint input region during the second phase. The first area 310may be displayed as a white region or a region with a predeterminedcolor. The bright screen may be still displayed on the second area 320during the second phase.

The touch sensing circuit 114, via the first interface circuit IF1,controls the fingerprint sensing circuit 116 to initiate the fingerprintscanning for the first area 310 and sense the fingerprint image of thefinger from the first area 310. The fingerprint sensing circuit 116transmits the fingerprint image to the application processor 230 for thefingerprint identification operation performed by the applicationprocessor 230. The operation of the electronic device 200 in theembodiment of the invention has been sufficiently taught, suggested, andembodied in the embodiments illustrated in FIG. 4 and FIG. 5 , andtherefore no further description is provided herein.

FIG. 7 is a flowchart illustrating steps in a method for fingerprintidentification according to an embodiment of the invention. Referring toFIG. 4 to FIG. 7 , the method for fingerprint identification of thepresent embodiment is at least adapted to the electronic device 200depicted in FIG. 4 , but the disclosure is not limited thereto. Takingthe electronic device 200 for example, in step S100, the touchcontroller 141 detects a touch event of the display panel 120 todetermine a first area 310. The touch event includes fingerprintidentification. In step S110, the touch controller 141 informs thedisplay driving circuit 112 via the second interface circuit IF2 todisplay the first area 310 with a higher brightness and the second area320 with a lower brightness. The first area 310 with the higherbrightness serves as the fingerprint input region. In step S110, thebacklight module 240 may increase the brightness of the backlight of theelectronic device 200 according to the instruction of the backlightcontroller. In step S120, the touch controller 141 wakes up thefingerprint sensing circuit 116 via the first interface circuit IF1 andcontrols the fingerprint sensing circuit 116 to initiate the fingerprintscanning for the first area 310 and sense the fingerprint image of thefinger from the first area 310. In step S130, the application processor230 receives the fingerprint image from the fingerprint sensing circuit116 and performs the fingerprint identification operation in the trustzone 232.

Other features of the method for fingerprint identification in theembodiment of the invention are sufficiently taught, suggested, andembodied in the embodiments illustrated in FIG. 4 to FIG. 6 , andtherefore no further description is provided herein.

FIG. 8 is a schematic block diagram illustrating an electronic deviceaccording to another embodiment of the invention. Referring to FIG. 4 ,the display driving circuit 112, the touch sensing circuit 114 and thefingerprint sensing circuit 116 may be formed in a single semiconductorchip that can drive and control the display panel 120 to perform thedisplay operation, the touch sensing operation and the fingerprintsensing operation. The electronic device 400 depicted in FIG. 8 issimilar to the electronic device 200 depicted in FIG. 4 , and the maindifference therebetween, for example, lies in that the display drivingcircuit 112 and the touch sensing circuit 114 may be formed in a firstsemiconductor chip 410 that can drive and control the display panel 120to perform the display operation and the touch sensing operation, andthe fingerprint sensing circuit 116 may be formed in a secondsemiconductor chip 420 which is different from the first semiconductorchip. The second semiconductor chip 420 may be a readout integratedcircuit (ROIC) chip. The ROIC is an integrated circuit configured toread signals from fingerprint sensors.

The first semiconductor chip 410 and the second semiconductor chip 420may communicate with each other via the first interface circuit IF1. Inaddition, the operation of the electronic device 400 in the embodimentof the invention is sufficiently taught, suggested, and embodied in theembodiments illustrated in FIG. 4 to FIG. 7 , and therefore no furtherdescription is provided herein.

FIG. 9 illustrates a voltage conversion operation according to anembodiment of the invention. Referring to FIG. 4 and FIG. 9 , thedisplay driving circuit 112 includes a first gamma curve GMA1 and asecond gamma curve GMA2. The second gamma curve GMA2 may be generatedaccording to the first gamma curve GMA1. The display driving circuit 112may drive pixels over the display panel 120 according to one of thefirst gamma curve GMA1 and the second gamma curve GMA2 during the firstphase. In an embodiment, the display driving circuit 112 generates gammavoltages corresponding to the respective first gray levels according tothe first gamma curve GMA1 for driving the pixels over the display panel120 during the first phase.

Further, the display driving circuit 112 generates gamma voltagescorresponding to the respective second gray levels according to thefirst gamma curve GMA1, and the generated gamma voltages are configuredto drive the pixels of the first area 310 during the second phase. Onthe other hand, the display driving circuit 112 generates gamma voltagescorresponding to the respective third gray levels according to thesecond gamma curve GMA2, and the generated gamma voltages are configuredto drive the pixels of the second area 320 during the second phase. Asillustrated in FIG. 9 , for a specified pixel data, an absolute value ofthe generated gamma voltage in the first gamma curve GMA1 is larger thanthat in the second gamma curve GMA2.

Therefore, the voltage conversion operation is performed such that thegamma voltages for driving the pixels of the second area 320 isconverted according to the second gamma curve GMA2 during the secondphase. Thus, as the backlight is adjusted to have a high brightness fordisplaying the first area 310, the dark screen (or a screen with normalbrightness such as the bright screen of FIG. 6 ) can be still displayedon the second area 320 during the second phase to compensate the highbrightness of the backlight.

FIG. 10 illustrates a data processing operation according to anembodiment of the invention. Referring to FIG. 10 , the display drivingcircuit 112 may drive pixels over the display panel 120 to display adark screen (or a bright screen) with respective first gray levelsduring the first phase. The respective first gray levels are notmodified during the first phase, and gamma voltages corresponding to therespective first gray levels may be generated according to the firstgamma curve GMA1. In FIG. 10 , the data processing curve DATA1 is alinear curve, i.e. a straight line. The display driving circuit 112processes input data to generate output data, e.g. the respective secondgray levels, to drive the pixels of the first area 310 during the secondphase according to the data processing curve DATA1. The respectivesecond gray levels are unchanged before and after the data processingoperation since the data processing curve DATA1 is a linear curve. Gammavoltages corresponding to the respective second gray levels may begenerated according to the first gamma curve GMA1. The generated gammavoltages are configured to drive the pixels of the first area 310 duringthe second phase.

On the other hand, the display driving circuit 112 processes input data,e.g. respective fourth gray levels, to generate output data, e.g. therespective third gray levels, to drive the pixels of the second area 320during the second phase according to the data processing curve DATA2.The respective fourth gray levels are modified as the respective thirdgray levels after the data processing operation. For example, accordingto the data processing curve DATA2, the input gray level 255 is modifiedas the output gray level 200, and the input gray level 127 is modifiedas the output gray level 50. Gamma voltages corresponding to therespective third gray levels may be generated according to the firstgamma curve GMA1. The generated gamma voltages are configured to drivethe pixels of the second area 320 during the second phase. In thepresent embodiment, Gamma voltages corresponding to the respectivesecond gray levels and the respective third gray levels may be generatedaccording to the same gamma curve, e.g. the first gamma curve GMA1.After the data processing operation, the respective gray levels aremodified, and the dark screen (or the bright screen) can be stilldisplayed on the second area 320 during the second phase to compensatethe high brightness of the backlight.

FIG. 11 is a flowchart illustrating steps in a method for driving adisplay panel according to an embodiment of the invention. Referring toFIG. 4 , FIG. 5 and FIG. 11 , the method for driving the display panelof the present embodiment is at least adapted to the electronic device200 depicted in FIG. 4 , but the disclosure is not limited thereto.Taking the electronic device 200 for example, in step S200, the touchsensing circuit 114 senses a touch of a finger to determine a first area310 corresponding to the touch on the display panel 120. In step S210,the fingerprint sensing circuit 116 senses a fingerprint image of thefinger corresponding to the first area 310 of the display panel 120. Instep S220, the display driving circuit 112 drives pixels over thedisplay panel 120 with respective first gray levels during a firstphase. In step S230, the display driving circuit 112 drives pixels ofthe first area 310 with respective second gray levels and pixels of asecond area 320 outside the first area 310 with respective third graylevels during a second phase.

The method for driving the display panel in the embodiment of theinvention is sufficiently taught, suggested, and embodied in theembodiments illustrated in FIG. 4 to FIG. 10 , and therefore no furtherdescription is provided herein.

In summary, in the embodiments of the invention, the touch sensingcircuit performs the touch sensing operation to determine a fingerprintinput region, and controls the fingerprint sensing circuit to initiatethe fingerprint scanning for the fingerprint input region via the firstinterface circuit without via an application processor. The scanningregion is a local region of the whole display panel. In addition, thetouch sensing circuit controls the display driving circuit to drivepixels with a display pattern indicating the fingerprint input regionvia a second interface circuit without via the application processor.Therefore, the method for the fingerprint sensing and identification ismore efficient. The fingerprint input region may have differentbrightness from that of the non-sensing region. The non-sensing regionis driven by lower voltages to compensate the high brightness of thebacklight when the fingerprint input region is displayed, such thatusers have good user experience.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed embodimentswithout departing from the scope or spirit of the disclosure. In view ofthe foregoing, it is intended that the disclosure covers modificationsand variations provided that they fall within the scope of the followingclaims and their equivalents.

What is claimed is:
 1. An electronic circuit adapted to drive a displaypanel comprising touch sensors and fingerprint sensors, the electroniccircuit comprising: a touch sensing circuit, configured to sense a touchof a finger and determine a first area corresponding to the touch on thedisplay panel; a fingerprint sensing circuit, configured to sense afingerprint image of the finger corresponding to the first area of thedisplay panel; and a display driving circuit, configured to drive pixelsof the first area with respective first gray levels and pixels of asecond area outside the first area with respective second gray levels,wherein the display driving circuit processes respective third graylevels to obtain the respective second gray levels, and the displaydriving circuit generates gamma voltages corresponding to the respectivefirst gray levels and the respective second gray levels according to asame gamma curve.
 2. The electronic circuit of claim 1, wherein at leastone of the respective third gray levels is higher than a correspondingone of the respective second gray levels.
 3. The electronic circuit ofclaim 1, wherein the display driving circuit further processesrespective fourth gray levels to obtain the respective first graylevels, wherein the respective first gray levels and the respectivesecond gray levels are obtained according to different data processingcurves.
 4. The electronic circuit of claim 1, wherein an averagebrightness of the first area is higher than an average brightness of thesecond area.
 5. An electronic circuit adapted to drive a display panelcomprising touch sensors and fingerprint sensors, the electronic circuitcomprising: a touch sensing circuit, configured to sense a touch of afinger and determine a first area corresponding to the touch on thedisplay panel; a fingerprint sensing circuit, configured to sense afingerprint image of the finger corresponding to the first area of thedisplay panel; and a display driving circuit, configured to drive pixelsof the first area with respective first gray levels and pixels of asecond area outside the first area with respective second gray levels,wherein the display driving circuit generates first gamma voltagescorresponding to the respective first gray levels according to a firstgamma curve in an operation mode, and the display driving circuitgenerates second gamma voltages corresponding to the respective secondgray levels according to a second gamma curve in the operation mode. 6.The electronic circuit of claim 5, wherein an absolute value of one ofthe first gamma voltages is larger than an absolute value of acorresponding one of the second gamma voltages for a specified pixeldata.
 7. The electronic circuit of claim 5, wherein an averagebrightness of the first area is higher than an average brightness of thesecond area.
 8. An electronic circuit adapted to drive a display panelcomprising touch sensors and fingerprint sensors, comprising: a touchsensing circuit, configured to sense a touch of a finger and determine afirst area corresponding to the touch on the display panel; afingerprint sensing circuit, configured to sense a fingerprint image ofthe finger corresponding to the first area of the display panel; a firstinterface circuit, wherein the touch sensing circuit, via the firstinterface circuit, controls the fingerprint sensing circuit to scan thefirst area and sense the fingerprint image from the first area; adisplay driving circuit, configured to drive pixels of the first area ofthe display panel; and a second interface circuit, wherein the touchsensing circuit, via the second interface circuit, controls the displaydriving circuit to drive the pixels of the first area, wherein theelectronic circuit is implemented in a single semiconductor chip, andthe first interface circuit and the second interface circuit aredisposed inside the single semiconductor chip.
 9. The electronic circuitof claim 8, wherein the touch sensing circuit, via the second interfacecircuit, controls the display driving circuit to drive the pixels of thefirst area with respective first gray levels and pixels of a second areaoutside the first area with respective second gray levels, wherein thedisplay driving circuit processes respective third gray levels to obtainthe respective second gray levels, and the display driving circuitgenerates gamma voltages corresponding to the respective first graylevels and the respective second gray levels according to a same gammacurve.
 10. The electronic circuit of claim 9, wherein at least one ofthe respective third gray levels is higher than a corresponding one ofthe respective second gray levels.
 11. The electronic circuit of claim9, wherein the display driving circuit further processes respectivefourth gray levels to obtain the respective first gray levels, whereinthe display driving circuit generates the respective first gray levelsand the respective second gray levels according to different dataprocessing curves.
 12. The electronic circuit of claim 9, wherein anaverage brightness of the first area is higher than an averagebrightness of the second area.
 13. The electronic circuit of claim 8,wherein the touch sensing circuit, via the second interface circuit,controls the display driving circuit to drive the pixels of the firstarea with respective first gray levels and pixels of a second areaoutside the first area with respective second gray levels, wherein thedisplay driving circuit generates first gamma voltages corresponding tothe respective first gray levels according to a first gamma curve in anoperation mode, and the display driving circuit generates second gammavoltages corresponding to the respective second gray levels according toa second gamma curve in the operation mode.
 14. The electronic circuitof claim 13, wherein an absolute value of one of the first gammavoltages is larger than an absolute value of a corresponding one of thesecond gamma voltages for a specified pixel data.
 15. An electroniccircuit adapted to drive a display panel comprising touch sensors andfingerprint sensors, comprising: a touch sensing circuit, configured tosense a touch of a finger and determine a first area corresponding tothe touch on the display panel; a fingerprint sensing circuit,configured to sense a fingerprint image of the finger corresponding tothe first area of the display panel; a first interface circuit, whereinthe touch sensing circuit, via the first interface circuit, controls thefingerprint sensing circuit to scan the first area and sense thefingerprint image of the finger from the first area; a display drivingcircuit, configured to drive pixels of the first area of the displaypanel; and a second interface circuit, wherein the touch sensingcircuit, via the second interface circuit, controls the display drivingcircuit to drive the pixels of the first area, wherein the electroniccircuit is implemented in at least two semiconductor chips comprising afirst semiconductor chip and a second semiconductor chip, wherein thefirst semiconductor chip comprises the touch sensing circuit and thedisplay driving circuit, and the second semiconductor chip comprises thefingerprint sensing circuit, wherein the second interface circuit isdisposed inside the first semiconductor chip, and the firstsemiconductor chip and the second semiconductor chip communicate witheach other via the first interface circuit.
 16. The electronic circuitof claim 15, wherein the touch sensing circuit, via the second interfacecircuit, controls the display driving circuit to drive the pixels of thefirst area with respective first gray levels and pixels of a second areaoutside the first area with respective second gray levels, wherein thedisplay driving circuit processes respective third gray levels to obtainthe respective second gray levels, and the display driving circuitgenerates gamma voltages corresponding to the respective first graylevels and the respective second gray levels according to a same gammacurve.
 17. The electronic circuit of claim 16, wherein at least one ofthe respective third gray levels is higher than a corresponding one ofthe respective second gray levels.
 18. The electronic circuit of claim16, wherein the display driving circuit further processes respectivefourth gray levels to obtain the respective first gray levels, whereinthe display driving circuit generates the respective first gray levelsand the respective second gray levels according to different dataprocessing curves.
 19. The electronic circuit of claim 16, wherein anaverage brightness of the first area is higher than an averagebrightness of the second area.
 20. The electronic circuit of claim 15,wherein the touch sensing circuit, via the second interface circuit,controls the display driving circuit to drive the pixels of the firstarea with respective first gray levels and pixels of a second areaoutside the first area with respective second gray levels, wherein thedisplay driving circuit generates first gamma voltages corresponding tothe respective first gray levels according to a first gamma curve in anoperation mode, and the display driving circuit generates second gammavoltages corresponding to the respective second gray levels according toa second gamma curve in the operation mode.
 21. The electronic circuitof claim 20, wherein an absolute value of one of the first gammavoltages is larger than an absolute value of a corresponding one of thesecond gamma voltages for a specified pixel data.
 22. A method fordriving a display panel comprising touch sensors and fingerprintsensors, and the method comprising: sensing a touch of a finger todetermine a first area corresponding to the touch on the display panel;sensing a fingerprint image of the finger corresponding to the firstarea of the display panel; driving pixels of the first area withrespective first gray levels and pixels of a second area outside thefirst area with respective second gray levels; processing respectivethird gray levels to obtain the respective second gray levels; andgenerating gamma voltages corresponding to the respective first graylevels and the respective second gray levels according to a same gammacurve.
 23. The method of claim 22, further comprising: processingrespective fourth gray levels to obtain the respective first graylevels, wherein the respective first gray levels and the respectivesecond gray levels are obtained according to different data processingcurves.
 24. The method of claim 22, wherein an average brightness of thefirst area is higher than an average brightness of the second area. 25.A method for driving a display panel comprising touch sensors andfingerprint sensors, and the method comprising: sensing a touch of afinger to determine a first area corresponding to the touch on thedisplay panel; sensing a fingerprint image of the finger correspondingto the first area of the display panel; driving pixels of the first areawith respective first gray levels and pixels of a second area outsidethe first area with respective second gray levels; generating firstgamma voltages corresponding to the respective first gray levelsaccording to a first gamma curve in an operation mode; and generatingsecond gamma voltages corresponding to the respective second gray levelsaccording to a second gamma curve in the operation mode.
 26. The methodof claim 25, wherein an average brightness of the first area is higherthan an average brightness of the second area.